Compact copy sheet input/output apparatus for an electrophotographic printing machine

Abstract

A compact machine architecture is realized by combining the functions of copy sheet feeding and stacking into one integral apparatus. The apparatus is initially completely filled with copy sheets to be moved into the transfer/fusing area of a copier/duplicator machine. A vertically translatable stacker tray is positioned above the copy sheet input and is moved downward in vertical synchronism with copy sheets being fed from the input stack. A paper feed roller, attached to the bottom of the tray, continually feeds the top sheet from the input supply. As the input sheet stack is consumed, the output (feed) copies are deposited onto the stacker tray. As operation continues the supply stack is depleted while the finished stack increases, but the overall volume occupied by the copy sheets remains the same. Since there is no "empty" volume in the apparatus, the size and cost of the unit is greatly reduced.

We claim: 
     
       1. An apparatus for feeding sheets of paper from a loading station into a processing station, and from the processing station into a sheet receiving station the loading station including: a fixed surface for supporting a supply of copy sheets to be fed,   means for feeding successive sheets from the top of said paper supply into said processing station, and   means for incrementally lowering said paper feeding means during said paper feed operation, and wherein said sheet receiving station includes a sheet stacker tray overlying said sheet loading station, said sheets being outputted to said stacker tray from said processing station and wherein said sheet feeding means is attached to the bottom of said sheet stacker tray.   
     
     
       2. The apparatus of claim 1 wherein said sheet stacking tray is separated by a distance d from the top sheet supplied on said copy sheet supply, said distance d being constant irrespective of the thickness of the sheets being fed. 
     
     
       3. An improved electrophotographic printing machine of the type in which a latent image is developed on a photoconductive member and a developed image transferred to a copy sheet and the developed image fixed at a fusing station, with successive copy sheets being supplied to said transfer station from a sheet loading station and exiting said fuser station into a sheet stacking station, whereby the improvement includes: a first, fixed horizontal surface for supporting the copy sheets being supplied to said transfer station and a second, horizontal surface overlying said fixed surface for separating the sheets being supplied from the transfer station to the sheet loading station, said second surface being vertically movable with respect to said first surface.   
     
     
       4. The printing machine of claim 3 further including sheet feeding means located beneath said second horizontal surface and adapted to feed individual sheets from the top sheet of said sheet loading station. 
     
     
       5. An input/output apparatus for feeding copy sheets into the transfer station of an electrophotographic printing machine and for receiving and stacking the copy sheets as they exit the fuser station of said printing machine, said apparatus comprising: a housing including at least a fixed bottom surface and a vertical side wall, said bottom surface forming the supporting surface for a supply of sheets to be fed into said transfer station,   a second vertically variable support surface for supporting copy sheets exiting the fuser station, and   means for varying the horizontal location of said second surface in response to the quantity of said sheets to be fed into said transfer station.   
     
     
       6. An apparatus for feeding sheets of paper into a processing station along a paper path length, the apparatus including: a fixed horizontal surface for supporting a supply of copy sheets to be fed,   a fixed vertical vacuum transport belt in operative relationship with said horizontal copy sheet support surface to transport copy sheets into said processing station,   means for feeding successive sheets in the top of said paper supply into vacuum transport engagement with said transport belt, and   means for incrementally lowering said paper feeding means during said paper feed operation so as to engage successive copy sheets at different locations of said transport belt while said paper path length continually varies during said paper feed operation.